The light radiation theory of light-emitting device is to generate light from the energy released by the electrons moving between the n-type semiconductor layer and the p-type semiconductor layer. Because the light radiation theory of light-emitting device is different from the incandescent light which heats the filament, the light-emitting device is called a “cold” light source.
The light-emitting device mentioned above may be mounted with the substrate upside down onto a submount via a solder bump or a glue material to form a light-emitting apparatus. Besides, the submount further comprises one circuit layout electrically connected to the electrode of the light-emitting device via an electrical conductive structure such as a metal wire.
Moreover, the light-emitting device is more sustainable, long-lived, light and handy, and less power consumption, therefore it is considered as a new light source for the illumination market. The light-emitting device applies to various applications like the traffic signal, backlight module, street light and medical instruments, and is gradually replacing the traditional lighting sources.